It is well-known that, with very few exceptions, rubber compositions are combined with various other materials before being cured and/or put into use. Some of these added materials improve the properties of the end product in service while others improve processing properties of the uncured compositions. In some instances, both effects may be achieved. It is also known that the various chemicals, pigments and other materials so used, both organic and inorganic, can interact in various ways to produce desirable or deleterious effects. For further discussions of rubber processing and materials used therein, see, for example, Encyclopedia of Polymer Science and Technology, published by John Wiley and Sons, New York (1970), particularly volume 12, page 280 and The Vanderbilt Rubber Handbook, R. T. Vanderbilt Company, Norwalk, Conn., 06855 (1968), particularly Sections 6, 7 and 8, beginning at page 337.
Benzofurazan oxides, and their analogs and isomers are known compounds, and many descriptions of them and procedures for their preparation have appeared. See, for example, Kaufman, et al., "Chemical Reviews," volume 9, page 429 and following (1959) and Mallory, et al., "Organic Synthesis" collective volume IV, pages 74 and 75, John Wiley and Sons, New York (1963). The following U.S. Patents also described procedures for preparing furazan oxides for various types: U.S. Pat. No. 4,185,018 to Fah; U.S. Pat. No. 3,528,098 to Shaw; and U.S. Pat. No. 2,424,199 to Ter Horst. In considering previous descriptions of furazan oxides and related compounds, it should be noted that nomenclature used for these compounds has not been consistant, in part due to uncertainty as to their structures and predominant isomeric form. For example, they have been described as furazan oxides, as ortho dinitroso benzenes or di (nitrile oxides). At other points, they have been referred to as isobenzofuroxanes, benzofuroxans, benzofurazan-N-oxides and benzofurazan oxides. It is believed that the latter term is the modern and preferred nomenclature, and it shall be used in this specification and the appended claims.
Studies of furazan oxides and related compounds in rubber have been reported. For example, Rehner and Flory state in Industrial and Engineering Chemistry, volume 38, page 500 et sec, that ortho dinitroso benzene is inactive in butyl rubber as a vulcanizing agent. In contrast, the para isomer is said to be very active by Rehner and Flory. U.S. Pat. No. 3,931,121 to Davis, et al., describes the curing of elastomer polymers with poly (chloronitroso) compounds. U.S. Pat. No. 3,931,106 to Crosby, et al., describes the use of dinitrile oxides, which can be generated in situ from furazans, in rubber cross-linking. In this regard, it should be noted that the aromatic furazan oxides of this invention cannot isomerize to di(nitrile oxides) because the bond between the adjacent carbon atoms is part of an aromatic ring. U.S. Pat. No 2,974,120 to Miller describes the use of nonaromatic furoxans as antioxidants and antidegradants in rubber. U.S. Pat. No. 2,905,582 to Coleman, et al., describes the use of nitroso compounds, including dinitroso compounds wherein the nitroso groups are on nonadjacent carbons in a method for bonding polyurethane resin to rubber bodies. Morita has described the use of N, 4-dinitroso-N-methyl aniline as an active chemical promoter for carbon black reinforcement of IIR, NR and SBR. See Rubber Chemistry and Technology, volume 49, page 119 and following (1976). Tanaka, et al., have reported studies of nitroso benzene in rubber where chain cleavage was observed in Kogyo Kagaku Zasshi 74(8), pages 1701-6 (1971).